11-03-2008
When a file is created by a process it gets an inode number and as it is filled with content it gets diskspace allocated.
It is possible to delete a file from one process while it is opened (and written to) by another. A "ls" or similar command will not show this file anymore, still the diskspace (as well as the inode) occupied by the file will remain occupied as long as the process is running. When the process is killed the inode as well as the diskspace is relinquished immediately. In your case tell the software developers that their scripting is bad and/or their software is even worse, because they must somewhere open files which they do not close. Not cleaning up - that is: releasing the resources you allocate - is as bad a behavior in software development as it is in housekeeping
Historically speaking this is one of the worser pranks you could play on your "favourite" systems administrator: create a file (prefereably named with a nonprinting character like "0x255" for instance) in /tmp and write to it from an insuspiciously named background process. Then delete the file from the commandline while the process is running. Wait until /tmp is filled and watch your sysadmin going nuts trying to find what it is - because /tmp seems to be empty and even the list of open file handles will (because of the nonprinting character) not reveal at first glance what is the culprit here.
Ahh, if forgot: a reboot spoils the party therefore do this on a production system where a restart is not so easy to manage.
bakunin
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